1. Field of the Invention
The present invention relates in general to a switch and a multiplexer including the same, and more particularly to a switch and a multiplexer including the same in which the variable resistor is disposed to reduce the signal interference and loss.
2. Description of the Related Art
A multiplexer is utilized for selecting one of multiple input signals as an output signal, and is extensively applied in various fields. For example, in a modern electronic system, multiple parallel signals are converted to a serial signal to reduce hardware cost for signal transmission. When the multiple parallel signals are converted to the serial signal, a multiplexer cyclically is utilized to select the parallel signals one after another, so that data corresponding to individual parallel signals becomes a serial arrangement in the serial signal outputted by the multiplexer.
When the conventional multiplexers are applied to the high-speed transmission applications, it is desired that the signal should completely pass through the transmission gate without signal losses and interferences. As shown in FIG. 1A, the parasitic capacitance usually exists in a multiplexer 1, which is caused by the capacitance produces by the adjacent electronic components or the circuit modules in the circuit. Such capacitance may affect the optimal efficiencies of the multiplexers, and especially, when it is produced in the high frequency signal.
The multiplexer may be composed of a plurality of switches, and the switches are disposed in serial along the path for conducting between a first input terminal In1 and a second input terminal In2 and an output terminal Out in the conventional multiplexer. However, as shown in FIG. 1B, the signal may be attenuated and interfered by the parasitic capacitance of the switch, and the unnecessary signal losses and interferences may be inevitably caused in the practical circuit, and hence the signal attenuation and distortion are caused by the parasitic capacitance effect. As a result, a switch and a multiplexer including the same which are able to reduce the signal attenuation and interferences are needed.